A (sad) tale of two polls. Actually, of one poll.

[MADem]

133. Nate Silver admitted he got lucky.

http://www.salon.com/2015/02/22/nate_silver_mostly_i_was_getting_credit_for_having_pointed_out_the_obvious_and_most_of_the_rest_was_luck/

Nate Silver: “Mostly I was getting credit for having pointed out the obvious — and most of the rest was luck”
My “perfect” 2012 forecast was fortuitous -- but contributed to the perception that statisticians are soothsayers
NATE SILVER

...I worry that certain events in my life have contributed to the hype cycle. On November 6, 2012, the statistical model at my website FiveThirtyEight “called” the winner of the American presidential election correctly in all 50 states. I received a congratulatory phone call from the White House. I was hailed as “lord and god of the algorithm” by The Daily Show’s Jon Stewart. My name briefly received more Google search traffic than the Vice President of the United States.

I enjoyed some of the attention, but I felt like an outlier – even a fluke. Mostly I was getting credit for having pointed out the obvious — and most of the rest was luck.

To be sure, it was reasonably clear by Election Day that President Obama was poised to win reelection. When voters went to the polls on election morning, FiveThirtyEight’s statistical model put his chances of winning the Electoral College at about 90 percent. A 90 percent chance is not quite a sure thing: Would you board a plane if the pilot told you it had a 90 percent chance of landing successfully? But when there’s only reputation rather than life or limb on the line, it’s a good bet. Obama needed to win only a handful of the swing states where he was tied or ahead in the polls; Mitt Romney would have had to win almost all of them.

But getting every state right was a stroke of luck. In our Election Day forecast, Obama’s chance of winning Florida was just 50.3 percent – the outcome was as random as a coin flip. Considering other states like Virginia, Ohio, Colorado and North Carolina, our chances of going 50-for-50 were only about 20 percent. FiveThirtyEight’s “perfect” forecast was fortuitous but contributed to the perception that statisticians are soothsayers – only with computers rather than crystal balls....